Phase transitions and ionic motions in solid trimethylethylammonium iodide studied by H-1 and I-127 NMR, electrical conductivity, X-ray diffraction, and thermal analysis
Phase transitions and ionic motions in solid trimethylethylammonium iodide studied by H-1 and I-127 NMR, electrical conductivity, X-ray diffraction, and thermal analysis
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DOI：
10.1002/bbpc.19961000406
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发表时间：
1996-04-01
期刊：
影响因子：
--
通讯作者：
Ikeda, R
中科院分区：
文献类型：
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作者：
Ishida, H;Furukawa, Y;Ikeda, R
研究了三甲基乙基碘化铵的H-1和I-127核磁共振、差热分析（DTA）、差示扫描量热法（DSC）、电导率以及粉末和单晶x射线衍射。在410 K以上、336 ~ 410 K之间和336 K以下分别得到了三种固相，分别为I、II和III。粉末x射线图谱显示，ⅰ相和ⅱ相分别为nacl型立方结构（a = 10.00(1)埃，Z = 4）和四边形结构(a = 8.430（5), c = 6.216(4)埃，Z = 2）。通过x -射线单晶衍射确定了第三相为正交结构(Pnam (#62), a = 11.294(4), b = 10.729（2), c = 7.158(6)埃，Z = 4）。在第三阶段，用H-1 NMR观察了CH3基团的C-3重定向和阳离子中整个（CH3）(3)N基团的C-3'重定向。在第二阶段，阳离子有望进行准各向同性取向。在相I中，阳离子进行了各向同性重取向，而球形阴离子进行了平移自扩散，H-1和I-127核磁共振以及电导率证明了这一点。因此，阶段II和阶段I是动态无序的阶段；尤其是第一阶段是高度无序的。从正离子和阴离子的动力学行为和热性能来看，相I可归类为具有nacl型结构的离子塑性相。
H-1 and I-127 NMR, differential thermal analysis (DTA), differential scanning calorimetry (DSC), electrical conductivity, and powder and single crystal X-ray diffractions were studied for trimethylethylammonium iodide. Three solid phases, named I, II, and III, were obtained above 410 K, between 336 and 410 K, and below 336 K, respectively. Powder X-ray patterns showed that Phase I and II have a NaCl-type cubic structure (a = 10.00(1) Angstrom, Z = 4) and a tetragonal structure (a = 8.430(5), c = 6.216(4) Angstrom, Z = 2), respectively. The structure of Phase III was determined to be orthorhombic (Pnam (#62), a = 11.294(4), b = 10.729(2), c = 7.158(6) Angstrom, Z = 4) by single crystal X-ray diffraction. In Phase III, the C-3 reorientation of CH3 groups and the C-3' reorientation of the whole (CH3)(3)N group in the cation were observed by H-1 NMR. In Phase II, the cation is expected to perform the quasi-isotropic reorientation. In Phase I, the cation was found to carry out the isotropic reorientation, while the spherical anion the translational self-diffusion, as evidenced by H-1 and I-127 NMR, and electrical conductivity. Phase II and I are, therefore, dynamically disordered phases; especially, Phase I is highly disordered. From the dynamical behaviour of the cation and anion, and thermal properties, Phase I can be classified into an ionic plastic phase with a NaCl-type structure.